Autonomous Well Valve

ABSTRACT

An autonomous well valve having a body that constitutes an actuator for opening and closing at least one first valve opening, wherein the body, that in operation is submerged, has an effective density that is equal or greater than the density of a first fluid and less than the density of a second fluid.

FIELD

There is provided an autonomous well valve. More precisely there isprovided an autonomous well valve having a buoyant body that constitutesan actuator for opening and closing at least one first valve opening.

BACKGROUND

When producing from, injecting into or maintaining a downhole well, aneed for opening or closing flow as well as directing fluids ofdifferent densities arises.

WO 2013/070235 discloses an apparatus for autonomously controlling fluidflow in a subterranean well, the fluid having a density which changesover time. An embodiment of the apparatus has a vortex chamber, a vortexoutlet, and first and second inlets into the vortex chamber. Flow intothe inlets is directed by a fluid control system which has a controlpassageway for directing fluid flow as it exits a primary passageway. Amovable fluid diverter positioned in the control passageway moves inresponse to change in fluid density to restrict fluid flow through thecontrol passageway. When fluid flow through the control passageway isunrestricted, fluid from the control passageway directs fluid exitingthe primary passageway toward a selected vortex inlet. When flow throughthe control passageway is unrestricted, flow from the primary passagewayis directed into the other vortex inlet.

US 2008/041580 shows an autonomous flow restrictors for use in asubterranean well. An apparatus is disclosed for use in a well whereinboth oil and gas are produced. The apparatus includes multiple flowblocking members having a density less than that of the oil. The membersare positioned within a chamber with the members increasinglyrestricting a flow of the gas out of the chamber through multipleoutlets. Another apparatus is disclosed for restricting production of atleast one undesired fluid which has a density different from a densityof a desired fluid. The apparatus includes at least one flow restrictorand at least one bypass flow restrictor. The bypass restrictor may havea greater restriction to flow therethrough as compared to the other flowrestrictor. The apparatus further includes multiple flow blockingmembers operative to increasingly restrict flow of the undesired fluidthrough the flow restrictor in response to an increased proportion ofthe undesired fluid.

WO 2014/081306 discloses an apparatus and a method for controlling fluidflow in or into a well, wherein the apparatus comprising: at least onehousing having: an inlet; and at least one outlet, one of which isarranged in a top portion or a bottom portion of the housing when in aposition of use; and a flow control means disposed within the housing,the flow control means having a density being higher or lower than adensity of a fluid to be controlled, and a form adapted to substantiallyblock the outlet of the housing when the flow control means is in aposition abutting the outlet.

US 2013/068467 discloses an inflow control device that controls the rateof fluid flow from a subsurface fluid reservoir into a production tubingstring. The inflow control device includes a particulate screen toremove particulate matter from the reservoir fluid, and at least twoflow restrictors. The flow restrictors are positioned oncircumferentially opposite sides of the inflow control device and areconnected by an isolated fluid passage. The flow restrictors limit theflowrate of reservoir fluid when the reservoir fluid has a high water orgas-to-oil ratio. The inflow control device also includes at least onepressure drop device that generates a pressure drop for the reservoirfluid in response to fluid pressure in the reservoir. The inflow controldevice also includes a choking apparatus that allows the flow ofreservoir fluid to be shut off and the particulate screen cleaned whilethe inflow control device is in place in hole.

SUMMARY

Generally, it is advantageous to open and close, alternatively redirectflow, in or close to the well itself. Lack of reliable valves suited forsuch operations, combined with difficulty related to the operation ofthem, has made such solutions less viable. A result is for instance,that vast quantities of water is produced to the surface from petroleumwells.

The purpose of the invention is to overcome or reduce at least one ofthe disadvantages of the prior art.

The purpose is achieved according to the invention by the features asdisclosed in the description below.

There is provided an autonomous well valve having a body thatconstitutes an actuator for opening and closing at least one first valveopening, and where the body, that in operation is submerged, has aneffective density that is equal or greater than the density of a firstfluid and less than the density of a second fluid, wherein the firstvalve opening extends from a conical recess in the first member, andwhere a first end portion of the body has a corresponding conicalrecess, and where a ball is placed between said two recesses, and whereconical recesses with a ball in between are provided at a second endportion of the body and in the second member, and where the body has alength that gives room for some axial movement between the first andsecond members, and where a ball race with at least one race ballsurrounds the body.

The term “effective density” equals the weight/volume ratio of the body.The body may be hollow and be made from materials of differentdensities.

Typically, the first fluid is a fluid having a lower density than thesecond fluid. The first fluid may be a fluid having lower density thanwater, and the second fluid may be water, or the first fluid may bewater and the second fluid may be a fluid having higher density thanwater.

The body is positioned between the first member and the second memberwhere the first member has the first valve opening with a valve closer,and where the second member has a body support that is inclined relativea valve center axis.

When the fluid surrounding the body is changed from the first fluid tothe second fluid, the body will rise in the fluid and move along theinclined body support of the second member due to direct or indirectcontact with the inclined body support. The body is thus also movedsomewhat along the center axis and thus actuating the valve closer toclose the first valve opening.

When the fluid is changed from the second fluid to the first fluid, theoperation will be reversed relatively the above.

A valve closer in the form of a ball constitutes a simple and reliableitem both for the closing operation and for movement between the firstmember and the body.

The conical recess in the second member may extend into a second valveopening.

Both end portions of the body and the corresponding first and secondmembers may thus have an identical form.

The body may be biased towards the second member when the body is in itssunken position. The first valve opening is thus kept open when the bodyis in a lower location and closed when the body is in its upperlocation. An example of biasing elements is race balls that support thebody and that is designed to position themselves at their lowestposition due to gravity.

In an oil producing well, the valve may be used for shutting offproduction if water enters the tool, and may be used for rerouting thewater to a different formation. If water disappears and oil again entersthe valve, oil production will resume. The same functionality may beused for gas production where gas stops and/or is rerouted to anotherformation. The tool may be used in a gas well for reducing waterproduction.

In injection wells, the valve may be used to control zonal flow byvarying the density of the injected fluids. The valve may be installedat selected places in the well and the direction of flow is opposite ofthe flow when the valve is used for instance as a waterstop valve. If alight fluid is injected, the valve is open and allow fluid to pass intothe formation. For instance, if water or a heavier fluid is injected thevalve will close. Many types of fluids may be used for injectionpurposes such as glycol water, methanol, various inhibitors, acids,gasses such as CO₂ and other fluids. The valve may be designed to allowflow of heavier or lighter fluids. Typical operations where this will beadvantageous is various workover operations.

The valve may be symmetrical about the center axis. The valve may thenbe functional in any rotational position. The actual design may renderthe valve to be operational in substantially any direction.

Such a design lend itself to be used blindly, which is without anyspecific orientation of the valve in the well.

The mechanism may also be used for other applications that requirededicated production/injection points such as water and gas injection(WAG) and steam assisted gravity drainage (SAGD), and workover and wellstimulation and operations where fluids of different densities arepumped into the well.

More than one valve may be positioned in series in a flow path. Thedifferent valves may operate at different fluid densities.

Thus, the valve according to the invention includes a mechanism that isactuated by a buoyant force that open or close one or several valves.Uses of the valve includes shutting off unwanted water or gasproduction, potentially rerouting these to a reservoir at another depth.Other uses are workover, stimulation or well intervention operationswhere fluids of selected densities can be placed in specific places inthe well. Other uses of the valve can be well operations where specifictools may be actuated by pumping fluids of different densities. Themechanism is also useful for injection wells, where for examplealternate water and gas injection are placed in different formations inthe reservoir.

As outlined above, the mechanism is autonomous, acting on variations influid densities. The mechanism has a high degree of symmetry resultingin that it can be installed blindly. This means that the mechanism needno orientation during installation in a well, and the mechanism worksfor all wellbore inclinations from vertical to horizontal. The mechanismmay be installed as a single unit or as multiple units spaced throughoutthe well.

The valve according to the invention provides a reliable, simple andcost effective way of autonomous flow control in a downhole well.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, an example of a preferred device is explained under reference tothe enclosed drawings, where:

FIG. 1 shows a principal sketch in cross section a valve according tothe invention in its open position;

FIG. 2 shows the same as in FIG. 1, but where the valve is in its closedposition;

FIG. 3 shows a section II-II of the valve in FIG. 2;

FIG. 4 shows a valve as in FIG. 2, but where a second valve opening isprovided;

FIG. 5 shows the valve positioned in a well where water is directed intoa different formation;

FIG. 6 shows a valve closer in an alternative embodiment;

FIG. 7 shows the valve in a different embodiment in its open position;

FIG. 8 shows the valve of FIG. 7 in its closed position; and

FIG. 9 shows a section VII-VII in FIG. 7.

DETAILED DESCRIPTION OF THE DRAWINGS

On the drawings, the reference number 1 denotes a well valve thatincludes a body 2 that in operation is submerged. The body 2 ispositioned between a first member 4 and a second member 6 in a housing8. In this preferred embodiment the members 4, 6 and housing 8 providesa room 10 for the body 2. Fluid may enter the room 10 via an opening 12.

At its first end portion 14 that is closest to the first member 4, thebody 2 is provided with a central conical recess 16. Similarly, thefirst member 4 is provided with a conical recess 16 opposing the conicalrecess 16 of the first end portion 14. A first valve opening 18 extendsfrom the conical recess 16 of the first member 4.

A ball 20 that here constitutes a valve closer 22, is positioned betweenthe said conical recesses 16.

Similarly, conical recesses 16 with a ball in between are provided at asecond end portion 24 of the body 2 and in the second member 6. Theconical recess 16 in the second member 6 constitute a body support 26.

The length of the body 2 is chosen to give room for some axial movementbetween the first and second members 4, 6. The valve 1 is symmetricalabout its central axis 27.

A ball race 28 with at least one race ball 30 surrounds the body 2. Theball race 28 is fixed to the housing 8. Gravity will ensure that the atleast one race ball 30 is positioned at its lowermost position in theball race 28.

A flange like ring 32 on the body 2 abuts the race ball 30 and bias thebody 2 towards the second member 6 and the body support 26 as shown inFIG. 1 where the fluid in the valve 1 has a lower density than theeffective density of the body 2. As the body is in its lowest positionand thus closest to the second member 6, the first valve opening 18 isopen for the fluid in the valve 1 to flow through.

As a fluid of higher density is flowing into the valve, the body 2 isrising in the fluid along the body support 26. The movement includes acomponent that moves the body 2 axially towards the first member 4 whenthe ring 32 is following the surface of the race ball 30.

The valve closer 22, here in the form of a ball 20, is closing the firstvalve opening 18.

In the section II-II shown in FIG. 3, the ball 20 is not shown.

FIG. 4 shows an embodiment where a second valve opening 34 that extendsfrom the conical recess 16 of the second member 6 is connected to a pipe36. In FIG. 4 where the body 2 has the same relative position in thevalve 1 as in FIG. 2, the second valve opening 34 is open while thefirst valve opening 18 is closed.

In FIG. 4 the valve 1 is shown in an equally functional inclinedposition.

FIG. 5 shows a tubing string 38 that is extending into a well 40 in theground 42. A valve 1 is included in the tubing string 38. The pipe 36 isextending from the valve 1 and into a formation 44 in the ground 42.

When the well 40 is producing water, the body 2 of the valve 1 will bein the position shown in FIG. 4. Water will thus be directed via thesecond valve opening 34 and the pipe 36 to the formation 44.

A different valve closer 22 in the form of a seat valve is shown in FIG.6.

In another embodiment shown in FIGS. 7, 8 and 9, a tube 46 is passingthrough the valve 1. At each end portions 14, 26 there is spaced outthree balls 20 with related conical recesses 16 for increased flowcapacity. The balls 20 are not shown in FIG. 9.

1. An autonomous well valve having a body that constitutes an actuatorfor opening and closing at least one first valve opening, and where thebody, that in operation is submerged, has an effective density that isequal or greater than the density of a first fluid and less than thedensity of a second fluid, wherein the first valve opening extends froma conical recess in the first member, and where a first end portion ofthe body has a corresponding conical recess, and where a ball is placedbetween said two recesses, and where conical recesses with a ball inbetween are provided at a second end portion of the body and in thesecond member, and where the body has a length that gives room for someaxial movement between the first and second members and where a ballrace with at least one race ball surrounds the body.
 2. A deviceaccording to claim 1, wherein the conical recess in the second memberextends into a second valve opening.
 3. A device according to claim 1,wherein the body is biased towards the second member.
 4. A deviceaccording to claim 1, wherein the body has a flange like ring that abutsa ball.
 5. A device according to claim 1, wherein the valve issymmetrical about the center axis.